In a remarkable shift in tone eight days after canceling the summit, citing Pyongyang's "open hostility", Mr. Trump welcomed North Korea's former intelligence chief, Kim Yong Chol, to the White House on Friday, exchanging smiles and handshakes. "They are loyal to Kim Jong Un and no one else".
There were also widespread reports that North Korea helped Syria build a nuclear plant that was destroyed by Israeli bombing in 2007.
The South Korean government of liberal President Moon Jae-in has made it a top priority to engage the North in dialogue to resolve decades-old animosity and bring lasting peace, publicly pledging it would never pursue the collapse of its neighbor. "Kim Jong Un", Assad said, the North's state-run KCNA news agency reported, using the abbreviated version of the country's official name.
Mattis, speaking alongside his South Korean and Japanese counterparts, attempted to dial back expectations for the ongoing talks between the United States and North Korea.
His comments reportedly came as he received the credentials of North Korean ambassador Mun Jong-nam.
Syria and North Korea have been accused of co-operating on chemical weapons, but both deny the accusations.
Ken Gause, director of the International Affairs Group at CNA, said: "If Kim Jong Un is set on making peace with the USA and South Korea and dealing away at least part of the nuclear programme, he will have to put the KPA's influence in a box and keep it there".
Mr Assad was also quoted as saying that he was sure Mr Kim would "achieve the final victory and realise the reunification of Korea without fail".
President Donald Trump is due to meet with North Korean leader Kim Jong Un on June 12 in Singapore with Pyongyang's nuclear arsenal high on the agenda and reports said that the reshuffle could be aimed at taming the military.
According to the South Korean Foreign Ministry, North Korea established diplomatic relations with Syria in 1966, opening its embassy in Damascus.
Mr. Trump revived the Singapore summit on Friday after canceling it a week earlier. But the North has given no clear hints about how far it could go toward meeting USA demands to dismantle its nuclear program.
"Take your time", Trump told Kim Yong Chol, a top aide to Kim.
The Korean People's Army is highly influential in the North and a centre of power in its own right.
But analysts say North Korea will be unwilling to cede its nuclear deterrent unless it is given security guarantees that the USA will not try to topple the regime.